Equity Incentive Plans - Nonvested Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Summary of the activity of stock option awards, shares
Options non-vested, beginning balance, shares	707
Granted, shares	475	500	300
Vested, shares	(226)
Forfeited, shares	(140)
Options non-vested, ending balance, shares	816	707
Options non vested, Wtd. avg. grant date fair value beginning balance (in dollars per share)	$ 3.93
Granted, Wtd. Avg. grant date fair value (in dollars per share)	3.64	$ 5.91	$ 2.09
Vested, Wtd. Avg. grant date fair value (in dollars per share)	3.21
Forfeited, Wtd. Avg. grant date fair value (in dollars per share)	4.13
Options non vested, Wtd. avg. grant date fair value ending balance (in dollars per share)	$ 3.86	$ 3.93
Stock Options
Summary of the activity of stock option awards, shares
Unrecognized compensation costs related to awards	$ 2.0
Expected weighted average period to recognize expense	2 years 8 months 12 days